![]() ![]() Results obtained from tunnel experiments agree well with the real situation but with enormous financial costs.Īnother high-fidelity method, CFD, has also been widely used to simulate the aerodynamic characteristics for different layouts. Scharpf and Mueller conducted wind tunnel experiments on different tandem wing configurations, to investigate the influence on the tandem wing aerodynamic characteristics by the horizontal distance, vertical distance, and the decalage between the two wings. ![]() conducted experiments on a series of multiwing configuration with finite span wings at Reynolds number of 1.4 e6, and the results indicated that the interaction between the two wings was favorable to the fore wing (the maximum lift coefficient increased), while the maximum lift coefficient of the hind wing did not decrease. To study the aerodynamic characteristics for tandem airfoil configuration, three different methods, including tunnel experiment, computational fluid dynamics (CFD) method, and theoretical calculation, were extensively used. Bottomley summarized the history of aircrafts with tandem airfoil layouts and pointed out the advantages and disadvantages of that kind of design. Researches on tandem airfoil configuration with its unique aerodynamic advantage were conducted for decades. IntroductionĬompared to the traditional layout, the induced drag for tandem airfoil configuration is smaller and the wingspan can be reduced with the same stiffness, for the reason that the two wings in tandem airfoil configuration are all generating positive lift. Besides, it will also be beneficial for the lift characteristic when the incidence angle and the wingspan of fore wing are appropriately declined or if the incidence angle and the wingspan of hind wing are appropriately increased. From the results, it can be seen that the bigger negative gap and stagger can produce better lift characteristic for tandem wing configuration. By varying the design parameters, such as the gap, the stagger, the incidence angle, the wingspan, the taper ratio as well as the aspect ratio, a series of tandem wing configurations are tested to analyze the lift coefficient and the induced drag of each lifting surface. The accuracy of the numerical solutions obtained by the method has been validated by the data obtained from computational fluid dynamics and tunnel experiment. In that method, the form of Fourier sine series is used to express the variation of the section circulation which changes continuously along the wingspan. In accordance with Prandtl’s classical lifting-line theory, a method to calculate the section lift coefficient for the tandem wing configuration or multiple-lifting-surface system is presented. The new drag and Nusselt number correlations are expected to improve the accuracy of Euler-Lagrangian simulations of non-isothermal particulate flows comprising ellipsoids or spherocylinders.In tandem airfoil configuration or multiple-lifting-surface layouts, due to the flow interaction among their lifting surfaces, the aerodynamic characteristics can be affected by each other. On the other hand, the Nusselt number correlation proposed for a spherocylinder is valid for Ar = 4 and Re ≤ 500. ![]() The Nusselt number correlation for prolate ellipsoids is valid for 1 ≤ A r ≤ 4 and Re ≤ 500. The average relative deviation between the drag correlation and the fitting data is 9.4%. Based on the simulation data and the data from literature, a drag correlation for oblate ( 0.2 ≤ A r < 1 and 1 ≤ R e ≤ 100) and prolate ( 1 ≤ A r ≤ 5 and 1 ≤ R e ≤ 2000) ellipsoids has been developed to broaden the range of applicability of existing drag correlations. Moreover, we observe that the drag coefficients and Nusselt numbers for a prolate ellipsoid of aspect ratio 4 and a spherocylinder of aspect ratio 4 are comparable with a maximal relative deviation 5%. The Nusselt number for a spherocylinder of aspect ratio 4 evolves as sin 1.278 θ. A correlation for m has been developed for 1 < A r ≤ 4 based on the simulation data. m being a function of particle aspect ratio. However, the Nusselt number for prolate ellipsoids evolves as sin m θ, viz. θ being the incident angle of the particle. The simulation results demonstrate that the drag coefficient for ellipsoids and a spherocylinder evolves as sin 2 θ, viz. In this work, the thermal lattice Boltzmann method with immersed moving boundary conditions has been employed to calculate the drag coefficients and Nusselt numbers for isolated axisymmetric nonspherical particles in uniform flow for a wide range of Reynolds numbers ( Re) and aspect ratios ( Ar). ![]()
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